Disorders of consciousness (DOC) are the result of a severe brain injury. These conditions have become more frequent as advances in emergency medicine have led to a better survival rate after brain lesions. The assessment of DOC patients at VA facilities relies primarily on observed motor output. However, this assessment is often challenging due to the sensory, motor and cognitive disabilities resulting from the brain injury. This issue is particularly critical since the diagnosis and prognosis has important ethical and medical consequences in regard to the selection of care, treatment, and end-of-life decisions. Consequently, families of DOC patients often struggle in making long-term decisions, and an alternative methodology could help them in this process. For all of these reasons, there is a growing effort at several specialized centers around the world to develop neurophysiological methods that could assist with the assessment of DOC patients. The current perspective is that improving the evaluation of DOC needs a multidimensional approach in which several neurophysiological markers are combined. The VA could play a significant role in this development by joining the existing expertise within the VA of clinicians specialized in DOC and of neuroscientists specialized in the analysis of neurophysiological signals and machine learning algorithms. Electroencephalography (EEG) provides high time-resolution signals of brain activity which makes it a method of choice for evaluating the neural dynamics of willful brain activity. We plan to combine the effort of the Emerging Consciousness Program from the Minneapolis and the San Antonio VA Health Care Systems to perform a pilot study and acquire preliminary EEG data of neural activity from DOC patients. These data will be compared to control subjects, both neurologically healthy and brain-lesioned patients without DOC. The healthy controls will provide a reference of healthy neural dynamics, whereas brain-lesioned controls will provide a reference of neural dynamics altered by brain lesions that does not affect conscious processing. The specific aims of this project are: (1) to create a collaborative interaction between members of the Emerging Consciousness Program, the Defense and Veterans Brain Injury Center, and the Brain Sciences with the scope of developing an EEG methodology for the evaluation of DOC patients. There has been no formal collaboration until now between clinicians and therapists from the ECP and neuroscientists from the DVBIC and the BSC. Such a collaboration would bring together complementary expertise within the VA in regard to DOC and the analysis and decoding of neurophysiological signals in regard to developing a methodology using EEG as a resource for the assessment of DOC patients. The current project would provide the first step for actualizing such a collaboration; (2) to perform a pilot study to collect preliminary data for the development of a future project aimed at the advancement of an EEG-based method of assessment of DOC patients. We will record EEG activity in DOC patients during resting state, during stimulation conditions with familiar vs unfamiliar stimuli, and during oddball tasks. In addition, behavioral assessment will be performed using a clinical scale (Coma Recovery Scale-revised). EEG data from DOC patients will be obtained across several weeks to evaluate potential changes in time. EEG data from DOC patients will be compared to control subjects, both neurologically healthy and brain-lesioned patients without DOC. Top-of-the art methods of analysis of brain signals will be used to extract features that discriminate the level of DOC, and that discriminate DOC patients from brain-lesioned patients without DOC. Patients admitted to the Minneapolis and the South Texas VA Emergency Consciousness Programs (ECP) will be considered for inclusion in the project. The goal of developing an EEG assessment protocol would provide VA sites with advanced methodology to serve severely brain injured veteran and active duty DOC patients and their families.